Preheat the oven to 400°F (200°C) and line a baking sheet with parchment paper.

Cut each salmon fillet lengthwise to create a pocket, being careful not to cut all the way through.

Brush each fillet with about 1 tablespoon of olive oil and sprinkle with salt and pepper.

Heat olive oil in a skillet over medium heat. Add spinach, Italian seasoning, paprika, cayenne, salt, and pepper. Sauté until spinach wilts, about 2 minutes.

Remove from heat and mix in jarred roasted red peppers, crumbled feta, and grated Parmesan cheese.

Stuff the salmon fillets with the spinach and feta mixture, packing it tightly inside the pockets.

Bake the stuffed salmon in the preheated oven for about 12 to 17 minutes, checking for doneness.

Let the salmon rest for a couple of minutes before serving with your choice of sides.